1. Field of the Invention
The present invention relates to a heat exchanger for exchanging heat between a first fluid and at least a second fluid of the type comprising a horizontal battery of long tubes which are supported at intervals by spacer devices. The first fluid circulates through the tubes and the second fluid flows about the battery of tubes transversely with respect to the tubes. The invention also relates to an atmospheric cooling tower comprising at least one heat exchanger of this type.
2. Description of the Prior Art
Atmospheric coolers, employed for cooling industrial waters by the atmosphere, may be of the "wet" type in which the water to be cooled is in direct contact with the air, or of the "dry" type in which the water travels through tubes around which the air is circulated, or of the "combined" type which combines these two methods. In coolers of the "dry" type and "combined" type, there are generally employed exchangers comprising finned or smooth metal tubes. In these two cases, for technical reasons, in particular internal and external corrosion of the tubes, and for economic reasons, there is a tendency to substitute smooth tubes of plastic material for the metal tubes. However, the construction of such heat exchange batteries of smooth tubes of plastic material presents delicate technical problems as synthetic materials have high thermal coefficients of expansion. For example, a tube having a length of around fifteen meters lengthens more than ten centimeters during a temperature change of about 15.degree.-20.degree. C. to a temperature of about 90.degree. C. Under these conditions, it will be understood that the installation of such batteries of tubes of synthetic material in a cooler is very difficult, since the tubes will lengthen to this extent when the cooler changes from its operative to inoperative states. If no particular precaution is taken, and these batteries of tubes of plastic material are mounted in a manner identical to that of conventional batteries of finned metal tubes, the tubes, which are supported at intervals by spacer devices so as to maintain them perfectly rectilinear and parallel to each other, will deflect or bend between the spacer devices and this will completely modify the geometry of the air passages defined between the tubes and considerably adversely affect the heat exchange capability of the battery. Further, when an installation is shut down during low outside temperature conditions, the tubes, in shrinking, exert very considerable forces on the support framework to which the battery is fixed at each end.